Data Center Alley

AWS · Equinix · Digital Realty · QTS · CloudHQ · Ashburn / Sterling, Virginia

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The resource footprint

Modelled average

In one day, this campus consumes about

43.250-metre swimming pools

Filled with the volume of water consumed by the campus and its electricity supply.

The actual estimate28,544,606 US gallons consumed

50-metre pools · 2 metres deep

Each diagram = 10 pools. Partial shading shows the remainder.

At the campus4,654,682 galMaking its electricity23,889,924 gal

Power-plant water may come from a different watershed. This is a volume comparison, not a claim that households lose this water.

At current operating capacity · Annual model spread evenly over time, not a live meter. Site estimates may differ by roughly ±40%.

Comparison sizes & sources

One pool = 50 × 25 × 2 metres = 2.5 million litres (about 660,430 US gallons). Pool depths vary; this is a defined comparison size.

One home-year = 10,791 kWh, the EIA’s 2022 average US residential electricity purchases. This excludes electricity generated at home and is a fixed US benchmark for all sites.

One car-year = 4.6 tonnes CO₂, the EPA’s typical passenger vehicle tailpipe estimate. The campus model is in CO₂e; the comparison expresses approximate climate scale, not equal mixtures of pollutants.

Monthly values are annual totals ÷ 12; daily values are annual totals ÷ 365. Actual demand varies. Comparisons cover the whole campus, including non-AI uses.

Water: see the numbers and sources

This is water used up, mainly through evaporation. Power-generation water may be used in a different watershed.

Total water use10,419M gal/yr

Evaporated on site1,699M gal

Making the power8,720M gal

Household comparison130,235homes, at 80,000 gal/year

Pressure on local water: Medium-High — a regional measure of demand compared with available water
Where the water comes from: Municipal potable supply
Cooling: Mixed — legacy evaporative towers alongside newer closed-loop halls
Basis: Fitted to a published figure of 1,700 million gallons a year
Claimed vs observed: Google's 2025 campus table (not the whole alley): Ashburn 53.2, Bristow 267.6 and Leesburg 190.7 million gallons consumed. The 1.7 billion gallon cluster figure is all operators.

Air: see the numbers and sources

The totals include nitrogen oxides, sulphur dioxide and fine particles. They cover both this site and the power plants supplying it.

Nitrogen oxides1,917t/yr

Sulphur dioxide1,704t/yr

Fine particulates256t PM2.5

Health (EPA)$224M/yr

Health range: $77.3–224 million a year. Lower bound is EASIUR national mid-range; upper is EPA benefit-per-ton at a ~$12M VSL.
Statistical deaths: 18.6 a year at that VSL — a national-average conversion from tons, not a local concentration study.
Equals: 2,395,751 cars of NOx
Where it burns: PJM Dominion — Virginia
Generation mix: Gas 55 · Nuclear 30 · Coal 4 · Solar 5
Diesel backup: Loudoun County has 4,000+ permitted diesel generators across Data Center Alley. That count is county-wide, not this campus, so it is not modelled as this site's diesel fleet.
CO₂e: 6,708 kt/yr — climate, not air quality

The project, approvals and community concerns

Who asked for it: Effectively everyone — us-east-1 alone underpins a large share of consumer apps, SaaS and federal cloud
Who approved it: Loudoun County created the by-right PD-OP zoning in the 1990s; Dominion Energy interconnection; Virginia's sales-tax exemption on data center equipment renewed through 2035
What it serves: AWS us-east-1, the default region of the internet; plus most major colo and peering
IT capacity: 3,400 MW current capacity / 5,200 MW full-build scenario

The densest concentration of data centers on Earth — roughly a quarter of global colocation capacity in one county. Its growth is the single largest driver of PJM's record 2025 capacity auction prices, which raised bills across thirteen states.

ratepayer-cost disputewater-stressed basin

Keep this guide handy

39.0437°, -77.4875°

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Quote or share these estimates

Gigawatt Ledger (2026). Data Center Alley: water and air. https://gigawatt-ledger.pages.dev/site/ashburn/. Modelled from disclosed capacity; site-level error ±40%.

Include the estimate’s date, whether it describes current or proposed capacity, and its uncertainty. Get an embeddable card.

Gigawatt Ledger · September 2026. Water and air figures are estimated from public records and disclosed capacity. How we calculate them · Use this in your community.